(See cooking tip). Preheat oven to 220C, fan-forced. Line an oven tray with baking paper. Pat the pork belly dry with paper towel. Rub with 2 tsp oil and season generously with salt. Put pork, skin-side up, on the lined tray and roast for 40 mins or until skin starts to blister. Reduce heat to 180C and roast for a further 25 mins or until pork is cooked through. Rest for 10 mins.
Step 2 — Prep ingredients
Meanwhile, peel the ginger, then finely chop. Thinly slice the garlic. Thinly slice the white part of the spring onion. Cut the green part into thin batons.
Step 3 — Make ginger chilli crumb
Put the ginger, garlic, white part of the spring onion and 2 tsp oil in a small frypan over medium heat. Cook, stirring, for 2-3 mins until golden and crisp. Transfer to a bowl with a slotted spoon. Add ¼ tsp chilli flakes (you can omit the chilli flakes if you prefer) and a pinch of sugar, then season with salt.
Step 4 — Make slaw
While the pork is resting, finely shred the cabbage with a sharp knife or mandoline. Peel the cucumber into ribbons with a vegetable peeler. Put 3 tsp white wine vinegar and a pinch of salt in a large bowl. Add the cabbage and cucumber and toss to combine.
Step 5 — Heat bao buns
Remove the bao buns from the bag and put on a plate. Cover with a microwave-safe bowl and microwave for 2 mins or until fluffy and heated through. (Alternatively, follow the steaming instructions on the packet.)
Step 6 — Get ready to serve
Slice the pork belly and brush or spoon over the hoisin sauce. Fill the bao buns with the pork belly, some of the slaw and green part of the spring onion. Scatter over the ginger chilli crumb and serve with the remaining slaw.